1. Field of the Invention
The present invention relates to a colored photosensitive composition.
2. Description of Related Art
Colored photosensitive compositions, which are photosensitive compositions colored with a colorant, are useful as materials for forming color pixels constituting a color filter in color liquid crystal displays, color solid camera and the like, or black matrices. Conventionally known compositions contain a colorant(A), a binder polymer (B), a photo-polymerizable compound (C) and a photo-polymerization initiator (D).
For making color pixels or the like with these colored photosensitive compositions, for example, a colored photosensitive composition layer (1) is formed on a substrate (2) (see FIG. 1(a)), said layer (1) is exposed to light by irradiating a light beam (4) through a photo-mask (3) (see FIG. 1(b)) and then a development is conducted. By the development, a non-irradiated area (11), which is an area of the colored photosensitive composition layer (1) having not irradiated with the light beam (4), is removed, while an irradiated area (12), which is an area having irradiated with the light beam, is remained. Thus a color pixel or a black matrix (5) is formed (see FIG. 1(c)). The color pixel or the black matrix (5) formed in this manner is usually hardened by heat treatment after development in order to increase the mechanical strength.
It is desirable that the color pixel or the black matrix (5) has a thin thickness and is rectangular (see FIG. 2(a)) or forward-tapered (see FIG. 2(b)) in cross section. In order to form a sufficiently colored color pixel or the like (5) in spite of a thin thickness, the concentration of the colorant (A) contained in the colored photosensitive composition should be high.
Since, however, when, in a conventional colored photosensitive composition, the concentration of the colorant (A) is increased in order to form a color pixel or the like having a thin thickness, the obtained color pixel or the black matrix (5) tends to become reverse-tapered in cross section (see FIG. 2(c)).
The inventors have conducted extensive studies for developing a colored photosensitive composition that enables production of a color pixel or a black matrix having a rectangular or forward-tapered cross section even when the colorant is contained in a high concentration. As the result, they have found that the cross section of the obtained color pixel or the like could be a rectangular or forward-tapered cross section by adding a chain transfer agent (E), even when the colorant is contained in a high concentration. The present invention has been completed based on such finding.
The present invention provides a colored photosensitive composition comprising a colorant (A), a binder polymer (B), a photo-polymerizable compound (C), a photo-polymerization initiator (D) and a chain transfer agent (E).